Tow chain for conveyors

ABSTRACT

A chain of low silhouette having links forming a relatively smooth, continuous top surface except for certain spaced links which incorporate a recessed truck-pin-engaging notch. The links are joined by a vertical joining pin having opposed shoulders spaced from the ends of the pin which positively maintains the links assembled while the chain is in operation yet permits the chain to be easily and safely assembled or disassembled at any point in the chain. The combination provides a chain which can be operated in a shallow track within the floor. The links can be utilized to form a conventionally driven main chain. A slave chain can be driven from the main chain by either a freewheeling dog extending under both chains, engaged by both the driving chain and the slave chain, or by a dog welded to the underside of the slave chain and engaged by the underside of the main chain.

United States Patent [72] Inventor Robert Kramlner Farmington, Mich.

[21] Appl. No. 843,137

[22] Filed July 18, 1969 [45] Patented Sept. 28, 1971 [73] Assignee Rapistan Incorporated Grand Rapids, Mich.

[54] TOW CHAIN FOR CONVEYORS 25 Claims, 35 Drawing Figs.

Primary Examiner-Arthur L. La Point Assistant Examiner-Robert Saifer Attorney-Price, Heneveld, Huizenga & Cooper ABSTRACT: A chain of low silhouette having links forming a relatively smooth, continuous top surface except for certain spaced links which incorporate a recessed truck-pin-engaging notch. The links are joined by a vertical joining pin having opposed shoulders spaced from the ends of the pin which positively maintains the links assembled while the chain is in operation yet permits the chain to be easily and safely assembled or disassembled at any point in the chain. The combination provides a chain which can be operated in a shallow track within the floor. The links can be utilized to form a conventionally driven main chain. A slave chain can be driven from the main chain by either a freewheeling dog extending under both chains, engaged by both the driving chain and the slave chain, or by a dog welded to the underside of the slave chain and engaged by the underside of the main chain.

Pmmmmmn SHEEI 2 [IF 6 III w V w y MT! r 4 g 5 a m JKJ W C m D m 9 F FIG. 6 B4 row CHAIN son CONVEYORS BACKGROUND OF THE INVENTION The invention concerns chains used in towing trucks, and more specifically to subfloor chains in truck conveyor systems which mechanically guide and pull a truck along the floor by engaging a pin downwardly depending from the truck. The chains utilized in the past have experienced a number of disad vantages. For example, the chain utilized in U.S.-Pat.No. 2,816,5l6 has a high profile caused by the pin-engaging jaws 31 which project upwardly from the main chain by means of lugs. Because of the high profile or silhouette of the chain, a deep track is required, resulting in a higher cost than would be incurred if the track were shallower. The truck-pin-engagingjaws of the aforesaid patented device have an additional disadvantage in that they are not conducive to random-dropping the truck-pin at any location above the chain permitting the chain to automatically pick up the pin when the jaws move into position under the pin. Although the slope of the jaw 32 of the aforesaid patent might tend to cam the pin upwardly} and into engagement with the jaws if the chain is moving from right to left, when the chain direction is reversed, there will be no positive engagement of the truck-pin by the jaws. Still '25 patent is that all the links of the chain tend to wear against the another difficulty with the system disclosed in the aforesaid track. Thus, when one of the links is worn beyond its useful life, the same is generally true of the rest of the chain so that nothing can be salvaged from the chain.

Still other difficulties encountered by previous chains con-- cern both the assembly and disassembly of the chain and the synchronization of additional chains used on spur tracks in Although such a 90 orientation is not common inthe layout of the chain in the track, it could occur in the takeup part of the track. Some of the difficulties incurred in disassembling;

the chain result from the fact that not all of the links are separable from each other, restricting disassembly of the chain to a few restricted points along its length.

With regard to the use and synchronization of spur chains which cooperate with the main chain, in the past a customary method has been to operate and drive the spur chains by independent drive means, requiring initial and repeated synchronization of the drive motors of both the main chain and the spur chains. Such synchronization, if not done automatically, is time consuming. To do it automatically requires additional equipment resulting in higher. cost andmaintenance. The necessity of an additional, independent motor also increases costs.

SUMMARY OF THE INVENTION The invention concerns a novel chain which by means of its low silhouette allows a shallow track to the utilized. More specifically, the invention concerns a subfloor towing chain for engaging a truck-pin to tow a truck in a conveyor system, the chain comprising a plurality of links including a truck-pinen gaging link provided with a recessed notch therein, the links having, when assembled, a low silhouette and a flat pin upper surface devoid of upward projections or gaps large enough to engage the truck-pin or to cause excessive vibration and noise except for the notch formed by the truck-pin-engaging link. The assembled chain also has means in the bottom of spaced links for engaging a source of power. An interchangeable vertical pin is utilized to connect the links, the pin having shoulders thereon which include means for engaging one of the links and for seating the vertical pin in another of the links. Other links include cooperative retaining means for the vertical pin, the retaining means comprising means in the walls of the links for receiving the shoulders of the vertical pin in a prescribed orientation. Each of the links of the chain includes means for allowing the links to rotate at least with respect to its neighboring link about the vertical pin joining the links. The links equipped with the means for engaging the source of power also include means for riding across a wearing surface.

The aforesaid chain can be utilized either as a main chain or as a slave chain operating as a spur to a main chain. In the event the chain is a slave chain, means extending from beneath selected links in the main chain to a point beneath similar links in the slave chain provide power transfer from the main chain to the slave chain/The power transfer means may be mounted on a double chain independently of either the main chain or the slave chain, or it may be welded to one of the links on the slave chain.

The structure of both the main and slave chains provides a novel method of disassembly and assembly of the links forming the chains.

Accordingly, it is an object of the invention to provide a powered tow chain which requires a shallower hole and track in the floor for the location and use of the chain than heretofore possible.

It is a further object of the invention to provide a chain of the above character in which the truck-pin to be engaged by the chain can be dropped onto the chain regardless of the links currently underneath the truck-pin, and then automatically engaged by the chain.

It is still another object of the invention to provide a chain of the above character in which chain wear is restricted only to limited surfaces and these surfaces are present only on certain of the links rather than the whole chain.

A still further object of the invention is to provide a chain which can be used either as the main chain or as a slave chain, the slave chain being automatically and synchronously driven by the main chain.

It is a related object of the invention to provide a chain which can be readily assembled or disassembled at any point yet incorporating a positive safeguard against accidental disassembly.

Still another related object of the invention is to provide a chain of the above character which has a reduced cost of manufacturing.

Other objects and advantages of the invention will become apparent upon reference to the following drawings and detailed description. v,

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary, partially sectioned front elevational view of the main chain constructed in accordance with the invention;

FIG. 2 is a fragmentary, plan view of the chain illustrated in FIG. 1;

FIG. 3 is an exploded sectional view taken along the line IIIIII of FIG. 2;

FIG. 4 is a plan view of the top member of one of the links illustrated in FIG. 3;

FIG. 5 is a bottom view of the bottom member of the link illustrated in FIG. 4;

FIG. 6 is a sectional view taken along the line VI-VI of FIG. 3;

FIG. 7 is a sectional view taken along the line VIVII of FIG. 3;

FIG, 8 is a plan view of the drive-engaging link illustrated in FIG. 3;

FIGS. 9 and 10 are sectional views taken along the lines IX--IX and XX respectively of FIG. 3;

FIG. 11 is an exploded sectional view of one of the pusher links taken along the line XIXI of FIG. 2;

FIG. 12 is a plan view of the upper member of the link illustrated in FIG. 11;

FIG. 13 is a bottom view of the lower member of the link illustrated in FIG. 1 1;

FIG. 14 is a sectional view taken along the line XIV-XIV of FIG. 12;

FIGS. 15 and 16 are sectional views taken along the lines XVXV and XVIXVI respectively of FIG. 11;

FIG. 17 is a perspective view of the vertical pin joining the links;

FIG. 18 is a sectional view of the track and chain assembly taken along the line XVIIIXVIII of FIG. 19;

FIG. 19 is a fragmentary plan view of the chain assembled in its track;

FIG. 20 is a front elevational view, partially in section, illustrating the engagement by the chain of a truck-pin;

FIG. 21 is a side elevational view, partly schematic and in section, similar to the illustration of FIG. 20 but including, in addition, the drive means for the main chain;

FIG. 22 is an enlarged side elevational view of the drive connection illustrated in FIG. 21;

FIG. 23 is an elevational view similar to FIG. 1 except that a slave chain is depicted;

FIG. 24 is a sectional view taken along the line XXIV- XXIV of FIG. 23;

FIG. 25 is a bottom view taken generally along the line XXVXXV ofFIG. 24;

FIG. 26 is a plan view of both a main chain and a slave chain illustrating a power takeoff;

FIG. 27 is a sectional view taken generally along the line XXVIIXXVII of FIG. 26;

FIG. 28 is a plan view similar to FIG. 26 except that a different power takeoff for the slave chain is illustrated;

FIGS. 29 through 32 illustrate the process of disassembly of either the main chain or the slave chain;

FIG. 33 is a bottom view of the vertical pin illustrated in FIG. 17;

FIG. 34 is a side elevational view of the same vertical pin; and

FIG. 35 is a fragmentary sectional view taken along the plane XXXV-XXXV of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention relates to a chain located and powered within a floor 50 in a track 171 for the towing of a conventional truck 52 by engaging a downwardly depending truck-pin 54 within the chain (FIGS. 20 and 21). If the chain is a main chain, it is powered by a conventional caterpillar drive 56 which comprises a motor 58 driving a sprocket 60 by means of a chain 62 engaging a shaft 64 which mounts the sprocket, the sprocket in turn engaging an endless double chain 66 freely rotatably carried by another sprocket 68. The double chain 66 has secured to it as by bolts, in an upstanding position, lugs 70 which are attached to the chain so that successive lugs have the mirror image ofthe preceding lug (FIG. 22).

In accordance with the invention, a pusher link 80 is provided for engaging the depending truck-pin, the pusher link being connected to the rest of the chain by center links 100 and vertical pins 140. The pusher link is assembled from a top plate 82 formed with a U-shaped truck-pin-engaging notch 83 and a base 84 (FIG. 11). To join the base and the top plate together, means are provided including a boss 86 in the base penetrating through an opening 88 in the top plate when the two parts of the pusher link are assembled. The boss 86 is then staked to the top plate. To provide a flat upper chain surface, the top plate is formed in the shape of a U with its ends 89 tapered downwardly and outwardly. The two ends 90 of the base constitute the driving surfaces which can be engaged by the lugs 70 on the drive chain 66 (FIG. 22). To allow the pusher link to ride on the track 171, the ends 90 are provided at the bottom thereof with wear pads 92 (FIG. 11).

The center link 100, which is the link positioned adjacent to the pusher link, is formed as one piece (FIG. 3), the ends of the link being provided with means for permitting limited bending of the chain about a horizontal axis. That means includes bottom and top surfaces 101 of the endpieces 102 so shaped that those surfaces have a convex curvature. This curvature allows the endpiece 102 to rotate slightly either up or down between the top plate 82 and the base 84 between which the endpiece is engaged when the center link and the pusher link are joined. To extend the flat upper chain surface created by the flanges 89 in the top plate 82 of the pusher link, the top surface 104 of the central position of the center link is indented upwardly so as to be coplanar with the flanges 89. In addition to the use of coplanar top surfaces, the chain of the invention is formed so that the pusher link is joined to the center link with the ends of the flanges 89 positioned so close to the top surface 104 of the center link that a truck-pin cannot drop down into the gap 106 formed by the joint (FIG. 1). However, the gap 106 is large enough to allow the two links to rotate relative to each other. It is the narrowness of the gap 106, the use of the recessed notch 83 to engage the truck-pin, and the coplanar location of the flanges 89 and the top surface 104 of the center link which allow a truck-pin to be dropped anywhere along the chain and eventually picked up by the notch 83.

The elongated hole in the longitudinal direction in the center link serves as a takeup to compensate for wear and stretch in the chain, thus eliminating the necessity of a separate physical takeup device.

The pusher link and the center link constitute the basic two links forming the chains, be the chain a main chain or a slave chain. Slave chains in general are formed by alternating pusher links and center links joined in the manner hereinafter discussed. If the chain is a main chain, such as the chain 108 in FIG. 1, an additional link utilized with these previous two links is a spacer link 110 (FIG. 3), which has a base 112 with a body portion 114 generally dish-shaped downwardly, the edges of the dish being flanged outwardly to form bottom ends 116 of the spacer link. The ends 116 constitute drive surfaces to be engaged by the lugs 70 of the drive chain 66, as shown in FIG. 22. Thus, the ends of both the spacer links 110 and those of the pusher links provide drive-engaging surfaces. The bottom surfaces 118 (FIG. 3) of the ends 116 constitute the wear pads for the spacer link. Thus, the chain is entirely supported by the pusher and spacer links and wear is limited to the bottom members of these two links.

To provide a low silhouette and flat-riding surface for a loose truck-pin, a flat top plate 120 is staked to the base 112 by means of the boss 122 extending through an opening 124 in the base, the surface of the top plate being coplanar with the top surface of the flanges 89. As in the case of the pusher link 80, the spacer link is joined at both ends to a center link which is inserted in between the top plate 120 and the base 112 of the spacer link. In the case of the main chain, the predominant links are the spacer links and the center links, the pusher link being utilized on the order of one every sixteen feet.

To allow any one of these three links to rotate at least with respect to its neighboring link about the vertical pin 140 joining the links, the ends 90 of the base of the pusher link, the ends of the flanges 89 of the pusher links, the ends 116 of the base of the spacer link and the ends 126 of the top plate of the spacer link are arcuately shaped about a vertical axis eliminating projecting corners, thereby preventing interference when one of the links turns 90 with respect to the other.

In accordance with another aspect of the invention, each link is joined to its adjacent link by a vertical pin 140. The same vertical pin is utilized to join every two adjacent links so that the vertical pins throughout the chain are interchangeable. The vertical pin comprises (FIGS. 17 and 34) a cylindrical body 142 and a crossbar 142a forming a pair of diametrically positioned, noncircular shoulders 144 and 146. The crossbar 1420 is spaced from both ends of the body. To engage the center link during one stage of the process of assembly or disassembly, as hereinafter described, the crossbar has flat sides 148 parallel to the axis of the cylindrical body 142. To seat the vertical pin in the base 84 of either the pusher link 80 or the base 112 of the spacer link 110, the shoulders are provided with a shallow bottom surface formed by the two planes 151 and 152 intersecting at an obtuse angle 150.

To accommodate the vertical pin, the links are formed with the following described openings. To accommodate the cylindrical body 142 of the vertical pin, circular openings 154 are provided in both the top plate 120 of the spacer link (FIG. 4) and in the flanges 89 of the pusher link 82 (FIG. 12). To allow the entire pin to be passed through the base 84 of either the pusher link 80 or the base 112 of the spacer link 11 0, slotlike openings 156 are provided. The openings 156 are elongated lengthwise of the link to allow the crossbar 142a of the pin 140 to pass through only if the crossbar 142a is positioned lengthwise of the link. To allow the pin to pass through the center link 100 with the crossbar positioned lengthwise of the. center link, slotlike openings 158 are provided adjacent eachend of the center link. The width of the openings 154 and 158 is less than the length of the crossbar 142a. Since it is unnecessary for the crossbar 142a to pass entirely through the center link, an elongated, downwardly opening recess could be substituted for the slotted opening. The top of the recess would be closed and its depth would only be that necessary to receive the crossbar 142a.

A notch or socket 160 is formed in the upper face of both the bases 84 and 112 (FIGS. 3, 11 and 35). This notch is elongated transversely of the links and is of sufficient length to accommodate the crossbar 142a. Its width is only sufficient to receive the crossbar. The bottoms of these notches 160 are shaped to accommodate and match the U-shaped bottom surface of the crossbar 142a. The depth of the notches is such that a small part of the top of crossbar 142 a projects above the surface 112 and will be accommodated by recesses in surface 101 of center link 100. The purpose of this is to prevent the assembly of center link 100 to either pusher link or spacer link should center link be turned upside down. Center links in.

that position would interfere with the drive dog and wouldv thus become an unwanted pusher link.

If a center link should be inserted upside down at assembly while the links are aligned and the pin 140 is passed through the bottom all the way up with crossbars in the center link and then the links are turned 90 with respect to one another, the

pin will drop. If the center link is not right side up, it is not possible to turn links from their 90 relationship to one another. This immediately alerts the assembler to the error.

The same pin 140 is used to connect all the links and the same locking arrangement is used in all cases.

The overall dimensions of the chain will obviously vary, depending on the size of the load and the power supplied. However, a representative chain is 1% inches wide, and by means of the low silhouette design of the links such a chain is only 1% inches high, a considerable reduction in the height heretofore used.

Because of the low silhouette provided by the chain constructed by the aforesaid links, the track 171 utilized in combination with the chain also has a low silhouette, being much reduced in height over the conventional track. The track 171 in which the chain rides is a U-shaped member 172 having a wear plate 174 at the bottom inside of the U and guide rails 176 welded to the inside of the upstanding members forming the U. To take advantage of the low profile of the chain, the guides 176 are positioned immediately above the top surface of the chain. Thus, as illustrated in FIG. 18, the guides 176 are immediately above the top of a pusher link 80. Because the top of the pusher link coincides and is coplanar with the top surfaces 104 of the center link 100 and/or the top surface 120 of a spacer link 110, this positioning of the guide rails 176 suffices for the entire chain. The spacing between the guide rails 176 is sufficient to allow the truck-pin to engage the chain and to pass between them but sufficiently restricted to prevent any significant transverse movement. To positively lock the track in the floor, an anchor strip 178 is welded at 180 to the track, a portion of the arm being partly bendable away from the track to engage the material .forming the floor. The anchor strip is originally straight and seats flat against the side of the rail. It is only bent out to the shape illustrated in FIG. 19 at the time of installation. This greatly reduces warehouse space requirements and the cost of shipping.

Although the size of the track 171 will vary depending on the size ofthe chain, for a chain 1% inches wide, the track 171 is only 3 inches deep. This compareswith a conventional track which must be 7 inches deep to accommodate a chain of that width.

To allow the chain to be disassembled while in the floor and, if it is a main chain 108, to be driven by the caterpillar drive described above, the track 171 terminates at 181 at a station 182 as shown in FIG. 21.

As indicated previously, the chain constructed with the aforedescribed links can be the main chain 108 of a slave chain. Where there is a distinction between the type of chain, the letter a is added to the reference numeral to indicate that the link is being used in a main chain and b if it is used in a slave chain.

The invention eliminates the necessity for a separate motor for the slave chain since it is driven by a power takeoff from the main chain. As illustrated in FIG. 26, the main chain 108 moving in the direction of the arrow 183, passes through a station 184 where it moves parallel to the slave chain 186. Both chains are engaged by a dog 190 which transfers the motion of the main chain 108 to the slave chain 186. The dogs 190 are mounted at equally spaced intervals on a pair of endless chains 210 which pass over a pair of idler end sprockets. The dogs 190 extend beneath the chains and seat in the socket formed by a center link a in the main chain and the same socket formed by a center link 100b in the slave chain. This arrangement causes the slave chain to be driven synchronously with the main chain.

FIGS. 23, 24, 25 and 28 illustrate another embodiment of the power transfer for the slave chain. In this arrangement the dog is fixed to the slave chain. Thus, in FIG. 28, a slave chain 286 is driven by a main chain 108 moving in the direction of the arrow 183. Dogs 290 are welded to the bottoms of the center links 200b of the slave chain 286. This may be done at every link or only at selected ones. The dogs 290 project horizontally from the center links 200b and are offset downwardly (FIG. 24) to engage in the sockets formed beneath the center links 100a (FIG. 28) of the main chain. To facilitate entry of the dogs 290 into these sockets, their ends are chamfered at 292.

The slave chains are generally used as spur chains to temporarily remove the truck from the main chain for one purpose or another. One such purpose would be where the main chain passes through its takeup area wherein the links of the main chain assume an angular relationship which would not be traversable by the truck-pin. In that case, the truck-pin is shunted to the slave spur chain which moves the truck as it bypasses the takeup station. Any switching means capable of transferring the truck-pin from one chain to the other can be utilized, such as switches disclosed in the prior art. The switching means does not constitute part of this invention, and accordingly is not shown.

Because of the novel structure of the main chain and the slave chain utilizing the aforedescribed links, a novel and safe method of both assembly and disassembly of the chain is possible. Assembly of the chain can be initiated at any point and disassembly can be effected at any link.

Assuming a spacer link 110 and a center link 100 are to be assembled, the procedure is as follows. The top and bottom 112 of the spacer link are first subassembled and locked together by peening the end of the post 122. The end of the center link 100 is inserted between them and held aligned with the spacer link 110. The pin 140, with its crossbar 1420 extending lengthwise of the spacer link 110, is inserted from the bottom until the crossbar 142a is received entirely in the elongated opening 158 of the center link 100. The center link 100 is then rotated 90 to the position shown in FIG. 29. This rotates the crossbar 142a and aligns it with the notch 160 in the bottom portion 112 of the spacer link. The crossbar then drops into the notch 160 and the spacer link 110 is rotated back to its aligned position. This causes the sides of the slotlike opening 158 of the center link to seat over the crossbar 142a locking the pin against axial movement.

The interengagement between the U-shaped bottom surface of the crossbar 142a and the corresponding U-shaped bottom of the notch 160 properly position the pin and hold it against any tendency to try to rotate when the chain is in use.

Assembly of the center link 100 to a pusher link 80 is identical. This assembly procedure is repeated until a chain of the desired length results. As the chain is assembled it can be installed in the track by introducing one end to the track as a suitable opening such as at station 182 (FIG. 21). When the two ends of the chain meet at this station, it is closed by installation of the last link. The slack in the chain resulting from having to rotate the last links with respect to each other is taken up by adjusting the position of a takeup sprocket at some point along the path of the chain. The use and construction of these takeup sprockets is well known in the art and thus need not be illustrated or described here.

The steps illustrated in FIGS. 29-32 are for the disassembly of a main chain. The disassembly procedure is the exact reverse of the assembly procedure. The portion of the chain to be disassembled is exposed such as at a station 182, the links initially being in alignment. Assuming the chain is to be opened at a joint between a pusher link and a spacer link, one of the spacer links and the center links must be rotated 90 with respect to the other. As illustrated in FIG. 29, the spacer link 110 has been rotated 90 counterclockwise with respect to the center link 100. When so oriented, the vertical pin 140 is pushed up to lift the crossbar 1421: out of the notch 160 and into the slotlike opening of the center link 100. The link which has been rotated initially, in the illustrated case, the spacer link 110 is rotated 90 back to its original aligned position while holding the vertical pin so that the crossbar 142a is maintained within the center link 100. When the links are once again aligned, the vertical pin 140 is free to drop out, opening the joint between the links. It will be readily apparent that while disassembly is an easy procedure, the structure provides assurance that the pin will not accidentally be released during chain operation. To permit pin release, the links must first assume a 90 relationship. Even should this occur, it is very unlikely the vertical pin 140 will be accidentally raised off the seat provided by the notch 160. The interengagement between the U-shaped bottom of the crossbar 142a and the matching bottom of the notch 160 coupled with the fact that the sidewalls of the notch 160 closely confine the pin, for all practical purposes eliminate any tendency of the pin to wedge its way out of the notch because of either pushing or pulling forces exerted by the chain. Having disassembled the chain and removed one of the links, the chain can be repaired by inserting a new link for the one removed. It can be shortened by reconnecting the chain. In all cases, if one link is removed and not replaced, so must be its adjacent link, inasmuch as every alternate link must be a center link. Irrespective of whether only a few or many links are replaced, the speed and ease with which it can be done materially reduces replacement costs and loses due to down time.

Because the chain has a lower silhouette and is of lesser cross section than conventional chains, it has less mass and less weight, thus, it has a lower wear factor and a lower power demand. Over an extended period of service, this results in substantial economy, both in replacement cost and in operating cost. The lower silhouette permits this track and chain to be used not only in new construction but to be installed in existing plants without interference with the service units already buried in the floor. Because of its shallow penetration of the floor, it can be passed over power, communication, water, steam and air conduits without conflict with the existing conduit work or in new construction requiring such conduits to be modified or buried much deeper to avoid interference. This, in itself, represents substantial economy and convenience at the time of installation. Because of its minimum floor penetration,

the use of this track in floors materially reduces the problem of structural weakening of the floor since most of the depth of the floor remains intact. in some installation, this is of no material significance but in others this can be a very important factor.

By limiting the areas of wear on the chain resulting from contact with the wear strip to the ends of the pusher and spacer links, a number of benefits result. When replacement is required, it is only necessary to replace these links and then it is only necessary to replace the bottom halves of these links. This results in substantial economy.

These and other improvements introduced by this invention make tow chain installation practical in a number of instances where they could not heretofore be used. Further, because of the lower initial cost and lower operating cost, this type of installation may now be used in smaller plants where heretofore the use of in-floor tow chain systems was not economically justified.

The embodiments of the invention in which an exclusive property or privilege is claimed and defined as follows:

1. A powered chain utilized in a floor for moving article carriers by engaging a downwardly depending tow-pin, said chain comprising a plurality of interconnected links including a center link, a pusher link and a spacer link, said pusher link having a recessed notch therein for engaging a tow-pin a removable vertical pin, said links being detachably low-pin, to each other in an end-to-end relationship by said removable vertical pin, wherein said center links cooperate with adjacent links at each end thereof to form a socket, closed at the top and opening through the bottom and sides of said chain for engaging a source of power, the ends of said adjacent links forming the end walls of said socket, said links having, when assembled, a low silhouette and a flat upper surface for sliding engagement with a tow-pin except for said notch formed in said pusher link.

2. The chain as defined in claim 1 wherein said pusher and spacer links each have a base and a top plate staked together, said top plate and said base having a boss on one and a hole in the other to accommodate said boss during the staking operation, said vertical pin passing through both said base and top plates.

3. The chain as defined in claim 2, wherein said pin has a crossbar spaced from both its ends and said base has means for seating said crossbar therein, the ends of said pin being substantially flush with the top and bottom surfaces of said chain.

4. The claim as defined in claim 3 wherein said crossbar has two planes intersecting at an obtuse angle forming its bottom surface, and said means has a bottom surface correspondingly shaped to receive said crossbar.

5. The chain as defined in claim 2 wherein said pin has a cylindrical body and a crossbar, each of said top plates has a hole therethrough to accommodate only said body of said vertical pin, each said center link has a hole which will accommodate in only one direction said crossbar, and said base includes means for retaining said vertical pin in a fixed orientation.

6. The chain as defined in claim 5 wherein said retaining means comprises means in the walls of said base for receiving said crossbar in a prescribed orientation, said receiving means including a notch in said wall closed at the bottom, the notch being only slightly larger than one of the dimensions of said crossbar so as to prevent the pin from rotating out of retention by said walls.

7. The chain as defined in claim 2 wherein said top plate of said pusher link has a body portion which is generally U- shaped, the top of the U" being flanged outwardly horizontally at both sides; said base of said pusher link being substantially flat except for downwardly extending means thereon for riding across a wearing surface; said top plate of said spacer link being flat; and said base of said spacer link having a body portion generally dish-shaped downwardly, the edges of the dish being flanged outwardly.

b. The chain as defined in claim 7, wherein said center link has a top surface coplanar with the top surfaces of said flanges of said pusher top plate.

9. The chain as defined in claim l and further having in combination therewith a second powered chain, said second chain having a plurality of links including a pusher link and a center link, said second chain links when assembled having a low silhouette and a flat upper surface for sliding engagement with a tow-pin except for the notch formed in said pusher links, and means in the bottom of certain of said links for engaging a source of power; and means extending from beneath said center link of said second chain to a point beneath said center link of the first-named chain for transferring power from said second chain to said first-named chain, whereby said first-named chain becomes a slave to said second chain.

10. The combination as defined in claim 9, wherein said transferring means includes a dog and a free-moving endless double chain mounted in the aforesaid floor for endless rotation in a plane perpendicular to the plane of said first-named chain, said dog being carried by said double chain and engaging both said first and slave chains and being driven by said first chain and serving as a means of motion transmission to said slave chain.

it. The combination as defined in claim 9, wherein said transferring means is a dog rigidly secured to the bottom of center link of said first-named chain, said dog projecting horizontally from the said center link into contact and engaging a link in said second chain adjacent to said second chain center link to drive said second chain.

H2. The chain as defined in claim 9 wherein said engaging means is a projection rigidly secured to one of said center links for transferring power between said chain.

13. The combination as defined in claim 1 wherein alternate ones of said links each have a bottom-wearing surface comprising two wearing pads on the bottom thereof, and further including a shallow track in combination with said chain, said track having a wear plate on the inside of the track for the sliding support of said wearing surface, said track being generally U-shaped with the wear plate fixed to the bottom of the U and a plurality of guide rails rigidly secured to the inside of the top portions of the U" immediately above the level of the top of said chain when said chain is seated in said track and partially closing the top of said track.

14. The combination as defined in claim l3 and further including an arm welded to the outside of said track, said arm being partly bendable away from said track to anchor the same in the floor.

15. A conveyor tow chain as described in claim ll wherein alternate ones of said links have downwardly projecting wear pads on the bottom face thereof.

16. A conveyor tow chain as described in claim wherein said wear pads are at opposite ends of said links.

17. A conveyor tow chain as described in claim 15 wherein those of said links having wear pads have an upper member and a lower member, said members being separable and said wear pads being on said lower members only.

113. A link for use in a subfloor towing chain, said link comprising:

a base member having means in the walls thereof for retaining a vertical pin in a fixed orientation, said retaining means comprising a notch in the walls of said base for receiving a projection on the vertical pin, said notch being closed at the bottom;

a top plate;

means for joining said base to said top plate; and

means on said base for engaging a source of power.

119. A conveyor tow chain for recessed installation in a floor and adapted to transmit movement to an article carrier through a tow-pin, said chain comprised of a plurality of adjacent links, said links collectively forming a fiat surface for sliding engagement with a tow-pin, said chain having pusher links incorporated therein at spaced intervals, each of said pusher links having an upwardly opening tow-pin-receiving recess interrupting said flat surface; a plurality of pins, one connecting each pair of adjacent links in end-to-end relationship, each of said pins having a securing element intermediate its ends; one of said links of each pair having receiving means for said securing element when said links are positioned at an acute angle to each other; the other of said links of each pair having means to engage said securing element and hold said pin against axial movement when said links are positioned relative to each other at an angle less than said acute angle.

20. A conveyor tow chain as described in claim 19, wherein alternate ones of said links have downwardly projecting wear pads on the bottom face thereof.

21. A conveyor tow chain as described in claim 20, wherein said wear pads are at opposite ends of said links.

22. In a chain having a plurality of links joined in end-to-end relationship with the end of one link being superimposed vertically over the end of at least a portion of the other link; a vertical pin connecting each adjacent pair of links for relative movement with respect to each other, the improvement of said chain comprising: said pin having a radially extending projection spaced from each of its ends; each of said links having an elongated opening therein for receiving said pin and its projection, said openings in both links being elongated parallel to the lengthwise dimension of said links; a transversely extending notch in said other link closed at the bottom and communicating with said opening; said pin and its projection being receivable in said elongated opening in said one link when said links are aligned with respect to each other; said projection being receivable in said transverse notch when said one link is turned with respect to said other link and locked in said notch when said links are turned to realign them.

23. In a chain having a plurality of links joined in end-toend relationship, one link of each pair having a bifurcated end and the end of the other links being received therein; a vertical pin connecting each adjacent pair of links for relative movement with respect to each other, the improvement in said chain comprising: a radially extending projection on said pin spaced from both of its ends; a socket closed on its lower side in the lower portion of said fabricated link to receive said projection therein when said links are positioned at an acute angle to each other; a portion of one link locking said pin against axial movement when said links are positioned with respect to each other at an angle less than said acute angle.

24. In a chain having a plurality of links joined in end-to-end relationship with the end of one link being superimposed vertically over the end of an adjacent link, a vertical pin connecting each pair of adjacent links for relative movement about the axis of said pin, the improvement of said chain comprising: a radially extending projection on said pin spaced from both its ends; an opening through both of said links to receive said pin, the opening in said adjacent link being elongated parallel to the long dimension of said link; a recess in said one link to receive said projection extending from said opening in the direction of the long dimension of said link; an upwardly opening socket in said adjacent link, said socket closed on its bottom and extending transversely of said link; said projection being insertable into said recess through said adjacent links when said links are aligned and receivable in said socket when said links are positioned at an acute angle to each other; said one link locking said projection in said socket and said pin against axial movement when said links are positioned at an angle less than said acute angle.

25. A conveyor tow chain for recessed installation in a floor and adapted to transmit movement to an article carrier through a tow-pin, said chain comprised of a plurality of adjacent links collectively having a flat surface for sliding engagement with a tow-pin, said chain having pusher links incorporated therein at spaced intervals, each of said pusher links having an upwardly opening tow-pinreceiving recess interrupting said flat surface, alternate ones of said links having downwardly projecting wear pads on the bottom face thereof, said alternate links having an upper member and a lower member, said members being separable and said wear pads being on said lower members only.

"H050 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,608,499 Dated pt m r 28, 19 1 Inventor) Robert Krammer k It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, Line 64:

"VI-VI I" should be VII-VII Column 8, Line 27:

"low-bin" should be joined Column 10, line 39:

"fabricated" should be bifurcated Signed and sealed this 25th day of April 1972.

(SEAL) EDWARD M. PLILTCHLJR, JR ROBERT GOTTSCHALK attesting; Officer Commissioner of Patents 

1. A powered chain utilized in a floor for moving article carriers by engaging a downwardly depending tow-pin, said chain comprising a plurality of interconnected links including a center link, a pusher link and a spacer link, said pusher link having a recessed notch therein for engaging a tow-pin a removable vertical pin, said links being detachably low-pin, to each other in an end-to-end relationship by said removable vertical pin, wherein said center links cooperate with adjacent links at each end thereof to form a socket, closed at the top and opening through the bottom and sides of said chain for engaging a source of power, the ends of said adjacent links forming the end walls of said socket, said links having, when assembled, a low silhouette and a flat upper surface for sliding engagement with a tow-pin except for said notch formed in said pusher link.
 2. The chain as defined in claim 1 wherein said pusher and spacer links each have a base and a top plate staked together, said top plate and said base having a boss on one and a hole in the other to accommodate said boss during the staking operation, said vertical pin passing through both said base and top plates.
 3. The chain as defined in claim 2, wherein said pin has a crossbar spaced from both its ends and said base has means for seating said crossbar therein, the ends of said pin being substantially flush with the top and bottom surfaces of said chain.
 4. The claim as defined in claim 3 wherein said crossbar has two planes intersecting at an obtuse angle forming its bottom surface, and said means has a bottom surface correspondingly shaped to receive said crossbar.
 5. The chain as defined in claim 2 wherein said pin has a cylindrical body and a crossbar, each of said top plates has a hole therethrough to accommodate only said body of said vertical pin, each said center link has a hole which will accommodate in only one direction said crossbar, and said base includes means for retaining said vertical pin in a fixed orientation.
 6. The chain as defined in claim 5 wherein said retaining means comprises means in the walls of said base for receiving said crossbar in a prescribed orientation, said receiving means including a notch in said wall closed at the bottom, the notch being only slightly larger than one of the dimensions of said crossbar so as to prevent the pin from rotating out of retention by said walls.
 7. The chain as defined in claim 2 wherein said top plate of said pusher link has a body portion which is generally U-shaped, the top of the ''''U'''' being flanged outwardly horizontally at both sides; said base of said pusher link being substantially flat except for downwardly extending means thereon for riding across a wearing surface; said top plate of said spacer link being flat; and said base of said spacer link having a body portion generally dish-shaped downwardly, the edges of the dish being flanged outwardly.
 8. The chain as defined in claim 7, wherein said center link has a top surface coplanar with the top surfaces of said flanges of said pusher top plate.
 9. The chain as defined in claim 1 and further having in combination therewith a second powered chain, said second chain having a plurality of links including a pusher link and a center link, said second chain links when assembled having a low silhouette and a flat upper surface for sliding engagement with a tow-pin except for the notch formed in said pusher links, and means in the bottom of certain of said links for engaging a source of power; and means extending from beneath said center link of said second chain to a point beneath said center link of the first-named chain for transferring power from said second chain to said first-named chain, whereby said first-named chain becomes a slave to said second chain.
 10. The combination as defined in claim 9, wherein said transferring means includes a dog and a free-moving endless double chain mounted in the aforesaid floor for endless roTation in a plane perpendicular to the plane of said first-named chain, said dog being carried by said double chain and engaging both said first and slave chains and being driven by said first chain and serving as a means of motion transmission to said slave chain.
 11. The combination as defined in claim 9, wherein said transferring means is a dog rigidly secured to the bottom of center link of said first-named chain, said dog projecting horizontally from the said center link into contact and engaging a link in said second chain adjacent to said second chain center link to drive said second chain.
 12. The chain as defined in claim 9 wherein said engaging means is a projection rigidly secured to one of said center links for transferring power between said chain.
 13. The combination as defined in claim 1 wherein alternate ones of said links each have a bottom-wearing surface comprising two wearing pads on the bottom thereof, and further including a shallow track in combination with said chain, said track having a wear plate on the inside of the track for the sliding support of said wearing surface, said track being generally U-shaped with the wear plate fixed to the bottom of the ''''U'''' and a plurality of guide rails rigidly secured to the inside of the top portions of the ''''U'''' immediately above the level of the top of said chain when said chain is seated in said track and partially closing the top of said track.
 14. The combination as defined in claim 13 and further including an arm welded to the outside of said track, said arm being partly bendable away from said track to anchor the same in the floor.
 15. A conveyor tow chain as described in claim 1 wherein alternate ones of said links have downwardly projecting wear pads on the bottom face thereof.
 16. A conveyor tow chain as described in claim 15 wherein said wear pads are at opposite ends of said links.
 17. A conveyor tow chain as described in claim 15 wherein those of said links having wear pads have an upper member and a lower member, said members being separable and said wear pads being on said lower members only.
 18. A link for use in a subfloor towing chain, said link comprising: a base member having means in the walls thereof for retaining a vertical pin in a fixed orientation, said retaining means comprising a notch in the walls of said base for receiving a projection on the vertical pin, said notch being closed at the bottom; a top plate; means for joining said base to said top plate; and means on said base for engaging a source of power.
 19. A conveyor tow chain for recessed installation in a floor and adapted to transmit movement to an article carrier through a tow-pin, said chain comprised of a plurality of adjacent links, said links collectively forming a flat surface for sliding engagement with a tow-pin, said chain having pusher links incorporated therein at spaced intervals, each of said pusher links having an upwardly opening tow-pin-receiving recess interrupting said flat surface; a plurality of pins, one connecting each pair of adjacent links in end-to-end relationship, each of said pins having a securing element intermediate its ends; one of said links of each pair having receiving means for said securing element when said links are positioned at an acute angle to each other; the other of said links of each pair having means to engage said securing element and hold said pin against axial movement when said links are positioned relative to each other at an angle less than said acute angle.
 20. A conveyor tow chain as described in claim 19, wherein alternate ones of said links have downwardly projecting wear pads on the bottom face thereof.
 21. A conveyor tow chain as described in claim 20, wherein said wear pads are at opposite ends of said links.
 22. In a chain having a plurality of links joined in end-to-end relationship with the end of one link being superimposed vertically over the end of at least a portion of the other Link; a vertical pin connecting each adjacent pair of links for relative movement with respect to each other, the improvement of said chain comprising: said pin having a radially extending projection spaced from each of its ends; each of said links having an elongated opening therein for receiving said pin and its projection, said openings in both links being elongated parallel to the lengthwise dimension of said links; a transversely extending notch in said other link closed at the bottom and communicating with said opening; said pin and its projection being receivable in said elongated opening in said one link when said links are aligned with respect to each other; said projection being receivable in said transverse notch when said one link is turned with respect to said other link and locked in said notch when said links are turned to realign them.
 23. In a chain having a plurality of links joined in end-to-end relationship, one link of each pair having a bifurcated end and the end of the other links being received therein; a vertical pin connecting each adjacent pair of links for relative movement with respect to each other, the improvement in said chain comprising: a radially extending projection on said pin spaced from both of its ends; a socket closed on its lower side in the lower portion of said fabricated link to receive said projection therein when said links are positioned at an acute angle to each other; a portion of one link locking said pin against axial movement when said links are positioned with respect to each other at an angle less than said acute angle.
 24. In a chain having a plurality of links joined in end-to-end relationship with the end of one link being superimposed vertically over the end of an adjacent link, a vertical pin connecting each pair of adjacent links for relative movement about the axis of said pin, the improvement of said chain comprising: a radially extending projection on said pin spaced from both its ends; an opening through both of said links to receive said pin, the opening in said adjacent link being elongated parallel to the long dimension of said link; a recess in said one link to receive said projection extending from said opening in the direction of the long dimension of said link; an upwardly opening socket in said adjacent link, said socket closed on its bottom and extending transversely of said link; said projection being insertable into said recess through said adjacent links when said links are aligned and receivable in said socket when said links are positioned at an acute angle to each other; said one link locking said projection in said socket and said pin against axial movement when said links are positioned at an angle less than said acute angle.
 25. A conveyor tow chain for recessed installation in a floor and adapted to transmit movement to an article carrier through a tow-pin, said chain comprised of a plurality of adjacent links collectively having a flat surface for sliding engagement with a tow-pin, said chain having pusher links incorporated therein at spaced intervals, each of said pusher links having an upwardly opening tow-pin-receiving recess interrupting said flat surface, alternate ones of said links having downwardly projecting wear pads on the bottom face thereof, said alternate links having an upper member and a lower member, said members being separable and said wear pads being on said lower members only. 